1. Field of the Invention
The present invention relates to an optical unit, and more particularly, to an optical unit used for a vehicle lamp. Further, the present invention relates to a vehicle monitor. Furthermore, the present invention relates to an obstruction detector.
2. Description of the Related Art
In recent years, a vehicle headlight that includes a mirror and can reciprocatively turn the mirror has been known (see Patent Document 1). The mirror reflects light emitted from a light source, which is formed of a plurality of light emitting elements, to the front of a vehicle. The vehicle headlight can scan an illumination region in front of a vehicle with light reflected by the mirror that is reciprocatively turned. The vehicle headlight includes an actuator that makes the mirror be reciprocatively turned.
Further, in the past, a method of detecting the light of a lamp of a vehicle, which is present on the front, using a camera has been known as a method of detecting a vehicle that travels on the front at night. However, this method has a possibility that the light reflected by a reflective object, such as a roadside delineator or a signboard, is erroneously detected as the light of a lamp of a vehicle. Accordingly, there is known a technique that discriminates a lamp of a vehicle, which is present on the front, from other reflective objects using a fact that the brightness of reflected light is changed when the brightness of a headlamp is reduced (see Patent Document 2).
Furthermore, various methods of detecting vehicles-in-front or pedestrians and obstructions, which are present in front of a vehicle, have been devised in the past. Patent Document 3 discloses a vehicle illumination device that includes an infrared sensor for detecting an object around a vehicle using infrared light and a visible light source irradiating the object with visible light when the infrared sensor detects the object. The vehicle illumination device scans a region in front of the vehicle in a predetermined pattern with infrared light, which is reflected by a reflecting mirror to be reciprocatively turned.